Detection and Quantification of Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus in Coastal Waters of Guinea-Bissau (West Africa).

Abstract

V.cholerae, V.parahaemolyticus, and V.vulnificus are recognized human pathogens. Although several studies are available worldwide, both on environmental and clinical contexts, little is known about the ecology of these vibrios in African coastal waters. In this study, their co-occurrence and relationships to key environmental constraints in the coastal waters of Guinea-Bissau were examined using the most probable number-polymerase chain reaction (MPN-PCR) approach. All Vibrio species were universally detected showing higher concentrations by the end of the wet season. The abundance of V.cholerae (ISR 16S-23S rRNA) ranged 0-1.2×10(4) MPN/L, whereas V.parahaemolyticus (toxR) varied from 47.9 to 1.2×10(5) MPN/L. Although the presence of genotypes associated with virulence was found in environmental V.cholerae isolates, ctxA+ V.cholerae was detected, by MPN-PCR, only on two occasions. Enteropathogenic (tdh+ and trh+) V.parahaemolyticus were detected at concentrations up to 1.2×10(3) MPN/L. V.vulnificus (vvhA) was detected simultaneously in all surveyed sites only at the end of the wet season, with maximum concentrations of 1.2×10(5) MPN/L. Our results suggest that sea surface water temperature and salinity were the major environmental controls to all Vibrio species. This study represents the first detection and quantification of co-occurring Vibrio species in West African coastal waters, highlighting the potential health risk associated with the persistence of human pathogenic Vibrio species.